Curiously, you didn't say, "when somebody says they went to college, its 'full of shit'". If people are as untrustworthy as you claim, it is a real concern. I assume you take steps to verify that everyone who claims to hold one actually does?
Of course, in programming specifically, it is so easy to verify expertise, relatively speaking, that observing any claim made by the applicant seems pointless.
Companies can verify academic credentials through third party services or the school directly. That's the whole point of credentials.
In programming it is very difficult to verify expertise. Programmers, especially self taught programmers, are usually very myopic. Someone will learn one technology, and then they determine a candidates overall expertise based on knowledge of that one technology. The problem is they've built up their entire ego based on learning just one thing and even got a job as a rails hacker or a javascript hacker or whatever. That person thinks that they know how to determine expertise: just ask a bunch of very specific rails questions. In reality there's a huge range of necessary expertise such as problem solving, debugging, interacting with people, using other languages and frameworks, databases, testing, operations. But the ego takes over and says, "I'm an expert in html, therefore html is all that's really important."
Now you might say that if the interviewer finds someone who can do the specific skill, what's the problem? The problem is that in a larger company, that one skill is a dime a dozen. How is the candidate going to stack up when there are 400 rails hackers that can also do lots of other things. As soon as its apparent the person can only do rails and is kind of dumb about other things, that's inviting huge criticism and job peril for the interviewers. Small companies can enjoy their ignorant bliss.
The other class of interviewers are hiring managers who's egos are by their very nature amazing experts in all fields and technologies, but who's brains know absolutely nothing about software.
I understand that you can, but I asked if you do? If you don't, the claim of having a degree holds no more water than claiming the title of "best programmer ever".
There was a high level executive from, I believe, Yahoo in somewhat recent times caught without having a degree, despite claiming to have one. It is clear that some people are definitely slipping through the cracks, even in large organizations who have the resources to do the requisite background checks. We also hear, over and over again, about the supposed college graduates who cannot even solve fizzbuzz which indicates that a lot of people are lying.
How many people, who actually have the skills and aren't foiled by fizzbuzz, are making their way into industry by lying about their education? I guess that is something we'll probably never know for sure, but what if it happens more often than we might suspect?
To answer your question I don't immediately think someone who claims to have a degree is full of shit about their degree. It takes a special kind of person to blatantly lie about an easily verifiable fact. I assume that any capable HR department is going to call the college registrar when conducting the background check. In the Yahoo CEO case, I don't think he started listing computer science until after getting the job.
Fizzbuzz failures happen because people don't code every day and can lose their edge in just a few weeks or someone did a degree that has very little practical material. Obviously, having a degree doesn't mean someone is a great programmer. Its just another tool to form a basis of trust.
Obviously a lot of people do lie their way in and do nothing or do negative work. That's why a lot of companies are so awful to work at if one is serious about their profession and actually trying to move things forward.
Of course, in programming specifically, it is so easy to verify expertise, relatively speaking, that observing any claim made by the applicant seems pointless.